SAT0076 Comparison of anti-interleukin-6 and anti-interleukin-6 receptor antibodies using in vivo functional systems

Background The multi-step assembly of the interleukin-6 (IL-6) signaling complex offers the potential for several therapeutic points of intervention in the treatment of rheumatoid arthritis; for example, targeting the cytokine IL-6, the IL-6 receptor (IL-6R; gp80), or gp130. Objectives The objective of this study was to compare affinity-matched anti-murine monoclonal antibodies (mAbs) that target either the IL-6 cytokine or the IL-6 receptor in a range of in vivo assays. Methods Affinity-matched anti-murine reagents 54E07 mAb (anti-IL-6) and 440-1 mAb (anti-IL-6R; gp80) were evaluated for their ability to inhibit either murine IL-6 or CFA-induced serum amyloid A (SAA). IL-6 is also known to have a significant role in B-cell function; therefore, these antibodies (Abs) were evaluated for their ability to inhibit dinitrophenyl (DNP)-specific Ab production. Furthermore, these Abs were dosed to steady state and their capacity to inhibit collagen-induced arthritis (CIA) in DBA-1 mice was evaluated. Results 54E07 mAb produced a ≥90% reduction in the SAA response to both IL-6 and CFA at a dose of 0.1 mg/kg (p Conclusions These murine in vivo studies strongly suggest that targeting IL-6 cytokine rather than the IL-6 receptor is the more efficient therapeutic approach for the treatment of autoimmune diseases such as rheumatoid arthritis. Disclosure of Interest None Declared